1. Field of the Invention
The present invention relates to a digital/analog (D/A) conversion apparatus for converting a digital signal into an analog signal.
2. Description of the Related Art
Generally, musical tone acoustic energy decreases as the frequency thereof increases. Accordingly, regardless of its high or low frequency band, when a musical tone audio signal is quantized with the same pitch into a digital signal, quantizing noise becomes relatively large in the high-frequency band. That is, in a playing apparatus such as a compact disk (CD) player or the like for playing a recording medium carrying digital data recorded thereon, the digital signal obtained by sound reproducing already includes quantizing noise in the high-frequency band. For example, in the case of a compact disk, since 16-bit digital data is obtained with a sampling frequency of 44.1 kHz, a 1 kHz sine wave having a minute level of -90dB changes only in the least significant bit (LSB) of the digital data, as shown in FIG. 13. Accordingly, the reproduced sound of an analog signal obtained by D/A converting digital data has poor-sounding high-frequency characteristics because of the quantizing noise.